1. Widest waterfall   Khône Falls   Niagara Falls   Grande Falls   Boyoma Falls   Yosemite Falls   Hint Half-n-half Clue   2. Nearest star to the Earth   Sun   Sirius   Alpha Centauri   Proxima Centauri   Pole Star   Half-n-half Clue   3. Coldest planet of our solar system   Neptune   Ganymede   Venus   Pluto   Saturn   Half-n-half Clue   4. Smallest planet of our solar system   Venus   Pluto   Mercury   Neptune   Mars   Half-n-half Clue   5. River with the greatest water flow   Mississippi-Missouri   Zambezi   Amazon   Nile   Hwang Ho   Half-n-half Clue   6. Planet of our solar system with fastest orbiting speed   Mercury   Pluto   Earth   Jupiter   Venus   Half-n-half Clue   7. Longest river   Hwang Ho   Mississippi-Missouri   Yangtze   Ob Irtysh   Amazon   Half-n-half Clue